I need a special tool ?

Has anyone any suggestions for a tool which would be "like" a camera iris, with a hole several mm long, but which can be varied in diameter from 1 (0.040 ") to 0.2mm (0.008"). I need to set the diameter fairly carefully, to just gently pinch a bundle of 70micron (0.0029"") optical fibres passed down the centre. The hole needs to be very circular and rigid, even as its closing......

Something kind of like the mechanism of a "pin-chuck" suggests itself, but wouldn't be very round in the limit.

Did you make this instructable?

I think this would work. Take a drill bit or other circular metal object of diameter maximum you need. Coat it with a thin layer of grease so silicon glue will not stick to it. mount the drill bit into the center of a 1/2 inch pvc end-plug that is also coated with the non stick grease. Fill the pvc endplug with silicone glue and let it dry/harden. Remove the hardend glue from the pvc endplug and also remove the .2mm drill bit from the glue. Now you have a flexible silicone round hole .2mm wide that you can squeeze using a simple hose-clamp. The hole will squeeze shut and should remain round. This should work if you only need to gently squeeze the fibers as you said. I kept trying to think of something METAL that would squeeze and retain its shape. I think that is impossible. Must use something that can be squeezed and will flex. Silicone glue might do it.

The only thing that comes to mind is a vascular stent. I'm not sure what the specific diameters are, but built with a metal mesh, they are designed to expand/contract as needed. It probably won't help you, since it's not really a "tool" per se, but if you get a hold of one, you might have the precise and gentle pinch you're looking for...

How about a braded device like the kids toy finger cuffs? That device, which is woven, works by contracting when the material inside, in the case of a child's fingers, tries to slide out. Once the material is inside the tubular accordian type band that should hold everything together perfectly. The tube could be woven to any desired diameter of contraction.

If you need something "like a camera iris", why not use a pair of iris mechanisms in line, like gripping the bundle with two hands? I'm sure you could machine a version with enough leaves to keep the bundle circular enough, and could link both sets so that they closed simultaneously?

Is there an "official" tool for the job, or are you inventing something?

If you're threading, does the order of the fibres matter? Could you use something like a funnel with a very shallow taper, down to a diameter of 201um, feed the bundle down it into whatever it is you're feeding it into?

That's right. I made an aluminium plate, and made up a test of 19 fibres bunged down the hole and glued in with proper araldite. I heated the assembly to 40 C, and the liquified epoxy ran into the hole very satisfyingly. Now I have a 2 mm high bump to lap off, for the test piece. Next, I want to make a 2 metre coherent bundle, in a stainless sheath like this.http://www.temperaturetechnology.com/documents/catalogue/SS_Armour.pdf

Sadly incoherent by design, and WAAAY to big. The fibres ideally want to be smaller than the Airy limit for the mirror feeding the spectroscope. That's why I've used a 30um core fibre for the prototype.

Hence the stent and Chinese basket ideas. I'm trying to form a 19 fibre coherent bundle. The ESO managed it for one of their spectroscopes, I've managed to terminate 19 fibres into a plate, with a microdrilled hole, calibrated to encircle 19 optimally packed fibres, with the expectation that the little buggers have litte choice but to go into some kind of order at the end.

About This Topic

Bio:I'm an Engineer, who originally inherited the family business (Thanks Dad (RIP JC Taylor, 1938-2011)) after working in it for 25 years, designing and building scientific instruments. In 2013, I was...read more »